The drinking response to systemic injection of isoprenaline has been used to study the decreased beta-adrenergic reactivity in hypothyroid rats. Using the same test, the beta-adrenergic responsiveness has been investigated in two models of experimental hypertension (DOCA-salt and Goldblatt two kidney one clip rats). Three weeks after induction of hypertension, control and hypertensive rats were injected subcutaneously isoprenaline (0.1 mg/kg) and the accumulative water intake at 1st, 2nd and 3rd hours was recorded. Isoprenaline induced a smaller drinking response in DOCA-salt hypertensive (DS) and DOCA-normotensive (D) rats than in normotensive (age control, normal uninefrectomized-salt and sham operated) or hypertensive Goldblatt two kidney one clip rats. Isoprenaline induced a 50% mortality in the mineral-corticoid treated D and DS rats. The present study suggests that the reduced beta-adrenergic response (water intake) and the rate of mortality observed in DOCA treated rats may be due to the absence of renin release after isoprenaline injection, as previously reported by us.